Wall board, sheathing lumber and the like



tree stares FAT CARL MARX, OF CHICAGO, AND ELTON R. DARLING, OF DANVILLE, ILLINOIS, ASSIGNORS TO PACIFIC LUMBER COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF MAINE No Drawing.

WALL BOARD, SEEA'I'HING LUMBER AND THE LIKE Application filed June 28,

set forth in the co-pending application of Elton R. Darling, Serial No. 372,224, filed. June 19, 1929.

As ordinarily prepared, redwood bark sheathing lumber has a comparatively absorbent and open texture. For some purposes this is undesirable, and it there-fore becomes necessary to treat said board or lumher with a sizing material, or the like, so as to cause a firmer adhesion of the fibres to each other.

However, it is desirable to maintain the interior of the board in its open and porous condition, while substantially treating or impregnating the outer portions of the board.

One of the objects of the present inven tion is to treat finished porous sheathing lumher or wall board of the type outlined with a material that, while in liquid condition, may be readily applied to the board, possesses the property of hardening comparatively rapidly and formin with the board a unitary structure where y the board is provided with a mineral comparatively non-absorbent surface which may have the additional prop erties of being fire-retardent. For example, we may. apply to the board, either after it has been dried or while undergoing drying, a thin coating of what inherently amounts to Sorel cement or the like, For example, we may make a suspension of magnesium oxide in .suficient hydrochloric acid to form a certain amount of magnesium chloride as a; result of the interaction of the magnesium oxide and the acid; having the suspension thin enough so that it may be applied to the surface of the board, on either or both sides thereof, by means of a spray gun or may be applied by rollers or even by a brush, although the spray gun is to be preferred as thereby the solution or suspension is caused to penetrate somewhat deeper into the board. This suspension of magnesium oxide in magnesium chloride soon after it penetrates the board will set into a cementitious body which closes up the pores of the board and also sur- 1929. Serial No. 873,052.

rounds the fibres near the surface thereof with a coating of magnesium oxychloride or S'orel cement. After the boards are dried, they will have thus been endowed with a penetrating coating infusible, insoluble and fire-proof material.

It is also possible to suspend the magnesium oxide in a solution of magnesium chloride, say of a strength of from 18 to 22 Baurn, the effect in either case being the same. If it is desired to vary the color of the material, which in the case of magnesium oxide is substantially white, suitable pigments may be added.

As an alternative method for providing the board with an interpenetrating surface of mineral material, it is also possible to apply thereto a creamy suspension of calcined gypsum, preferably of-a type which is Suficiently retarded in its setting so that the, material may be sprayed thereon much in the manner of paint. Such a suspension may be obtained by mixing calcined gypsum with Water in which a small amount of sodium phosphate has been dissolved, preferably the disodium phosphate, although known organic retarders of the setting of gypsum may employed with equal effect, the object being in either case so to retard the setting of the gypsum that the same will take place substantially simultaneously with the drying of the board.

A further alternative is the application to, v

the board of a thin suspension of neat Portland cement and suflicient water to form a sprayable'suspension. If it is desired to endow the board with particular resistance to certaintypes of insects, this may be accomplished by spraying the board with a suspension of zinc oxide in zinc chloride, which also has the properties of setting into a cementlike body.

We are aware of the use of solutions of organic sizes, glues, casein, and the like for the stifienin and water-proofing of wall board. We are a so aware of the use of said board as a base for plastering operations. We desire, therefore, to point out wherein our invention differs from the known application of cementitious material to the surface of a 7 of the board, the object being to reinforce and compacted felted redwood to coat the particles of the board with the mineral material without of necessity forming a distinct layer above the surface of the board.

Boards prepared in accordance with our invention may be employed as a plaster board, especially if. the material applied thereto is of the same nature as the material which penetrates the fibres, as thereby a particularly good bond is obtained. A further advantage, especially when using the board as a base for plastering, is the fact that the suction or absorbent power of the board has already been partly compensated by the presence of the hardened mineral material surrounding the fibres.

Instead of applying water for making up the solution of the magnesium chloride or for suspending the gypsum, we may employ the waste liquors resulting from the leaching of redwood bark, whereby we thus incorporate with the board all of the material originally contained therein, the tannic acid naturally present in these leach waters acting as a natural retarder for the settingof the gypsum, so that nothing further will be required than to suspend the calcined gypsum in these leach liquors. In case magnesium chloride solutions are prepared, there will be formed a certain amount of magnesium tannate which is particularly desirable as a component of the finished board as it acts as a fire-proofing agency.

The board prepared in accordance with our .invention has a substantially organic inner portion, consisting of redwood fibres (or other fibres, if they be used), while the outer portions of the fibres are provided with a coating of a set mineral cementitious substance which lends additional strength thereto and greatly diminishes the dusting usually encountered when handling redwood board.

We consider any suitable mineral cement as an equivalent for the Sorel cement, gypsum or Portland cement herein recited. The method of applying the cement is also purely a mechanical expedient and is immaterial in interpreting the hereunto appended claims.

. We claim:

1. A board consisting of an inner layer of compacted felted fibres and an outer layer of similar fibres which individually are encased in a cementitious material, there being insufficient of the latter to form a distinct layer on the surface of the board.

2. Plaster-board consistin of a mass of bark fibres, the outer layers of said fibres being provided with a coating of a set cement, the cement being insufficient in amount to form a substantially individual layer above the surface of the board.

3. Plaster-board consisting of a mass of compacted felted fibres, at least one side of said board having the fibres constituting the same provided with a coating of a set cement, the cement being lIlSllfllClGIlt in amount to form a substantially individual layer above the surface of the board.

4. The process of makin a building material in the form of a boar which comprises sizing redwood bark fibres, forming the same into a compacted board and spraying or otherwise applying to at least one surface of said board a penetrating coating of a cementitious material capable of setting into a hardened insoluble mass, and drying said board.

5. The process of making a building material in the form of a board which comprises sizing redwood bark fibres, forming the same into a compacted board and spraying the same with a suspension of a cementitious substance in the leach waters from the treatment of said redwood bark. V

6. The process of making a building material in the form of a board which comprises sizing redwood bark fibres, forming the same into a compacted board; suspending calcined gypsum in the leach-waters resulting from the leaching of said bark, and applying said suspension to said board in such manner that said suspension impregnates at least one side of said board to an appreciable depth and sets therein to a mass of hardened gypsum.

In witness whereof, we have hereunto subscribed our names.

CARL MARX. ELTON R. DARLING. 

